JP2013021979A - Bush cutter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve workability by reducing vertical vibration caused by the reciprocating motion of a piston and intercepting noise caused by the combustion of an engine, in an engine-type bush cutter.SOLUTION: A tubular cover 5, which has an axial line in the longitudinal direction, is provided to surround the whole of the engine 10 being the power source of a hand-held type bush cutter, and inside the cover 5, the engine 10 is held with a plurality of vibration control devices 30. The inner space behind the cylinder in the cover 5 is demarcated by a partition plate 40, and the demarcated underside is used as a space for suction of air and the upper side is used as a space for discharge of air and exhaust gas. A muffler 16 is provided in the upper space for exhaust. The vibration control device 30 is constituted mainly of a spring 31, and is fixed by a bolt 36 and a spring holder 32.

Description

  The present invention relates to a brush cutter, and more particularly, to a hand-held brush cutter with improved vibration reduction performance.

  In a hand-held brush cutter, as disclosed in Patent Document 1, a small engine is widely used as a power source. The engine is small and light and can obtain a large output, and has an advantage that it can work for a long time by supplying fuel. However, an engine has a demerit that vibration is larger than that of an electric motor because a piston reciprocates inside a cylinder and explosion occurs due to combustion of an air-fuel mixture. In recent years, noise and vibration regulations are becoming stricter in order to reduce the burden on workers, and there is a demand for further low noise and low vibration brush cutters.

JP 2007-259721 A

  As a vibration source of an engine type brush cutter, there are vertical vibration due to reciprocating motion of a piston and torsional vibration due to torque fluctuation. Among these, various measures have been taken for torsional vibration, and most of the torsional vibration can be removed. For vertical vibration, various measures are taken such as fixing an elastic body to a handle grip or reducing vibration transmitted to a human body (operator) via an elastic body between the handle and the main pipe. . However, since the deformation amount of the elastic body is minute, it is difficult to further improve the vibration damping effect. Further, if the deformation amount of the elastic body is increased, there is a risk that the feeling of rigidity is reduced and the comfort of the brush cutter is lowered.

  This invention is made | formed in view of the said background, The objective is to provide the brush cutter which can reduce the vibration transmitted to an operator by improving a vibration isolator.

  Another object of the present invention is to provide a brush cutter that reduces noise transmitted to an operator and prevents the intake or exhaust wind from hitting the operator.

  Still another object of the present invention is to provide a brush cutter that is easy to use and has high workability by forming a portion that contacts an operator during the operation of the brush cutter with a cover having a smooth shape.

  The characteristics of representative ones of the inventions disclosed in the present application will be described as follows.

  According to one aspect of the present invention, the engine, an output transmission shaft that transmits the output of the engine and a tool is attached to the tip, a main pipe through which the output transmission shaft is inserted, and an intermediate position of the main pipe are provided. A brush cutter having a handle for hand holding, and a cylindrical cover having an axis in the front-rear direction is provided so as to surround the entire engine, and the engine is held by a plurality of vibration isolators inside the cover. The front side of the cylindrical cover is narrowed down and connected to the main pipe, and the rear side is opened. The vibration isolator is disposed in a direction perpendicular to the axis of the output transmission shaft.

  According to another feature of the invention, the plurality of anti-vibration devices are arranged in parallel at regular intervals. The vibration isolator is, for example, a coil spring, and one end of the spring is fixed near the joint between the engine cylinder and the crankcase, and the other end is fixed to the cover. Preferably, four winding springs are used as springs, two springs are disposed horizontally on one end side of the engine, and two springs are disposed horizontally on the other end side of the engine. One end of each spring is attached to the cover via a spring holder, and the other end of each spring is fixed to a hole formed in a cylinder of the engine using a screw or a bolt.

  According to still another feature of the present invention, the internal space on the cylinder rear side in the cover is partitioned by a partition plate, one of the partitioned spaces is an air suction space, and the other is an air and exhaust gas discharge space. Used as The cover is formed with a flat portion on the lower side to serve as a mounting surface, and an upper end is formed with an acute angle. An engine muffler is arranged in the exhaust space. The engine is an upright engine in which the cylinder is arranged in the vertical direction, and the partition plate is provided in a horizontal direction so as to extend to the vicinity of the joint between the cylinder and the crankcase. Is done.

  According to the first aspect of the present invention, the brush cutter is provided with a cylindrical cover having an axial line in the front-rear direction so as to surround the entire engine, and the engine is held by the plurality of vibration isolating devices inside the cover. It is possible to realize a brush cutter having a good vibration reduction effect not only for vertical vibration due to reciprocation but also for torsional vibration due to torque fluctuation.

  According to the invention of claim 2, the front side of the cover is narrowed down and connected to the main pipe, and the rear side of the cover is opened, so that the entire engine can be covered and the engine noise is not easily transmitted to the operator. A brush cutter with a structure can be realized. Furthermore, since the vibration isolator is disposed in a direction perpendicular to the axis of the output transmission shaft, the space in the side portions of the cylinder and the crankcase can be used effectively, and the main body can be configured compactly. Also, with such an arrangement, it is possible to effectively suppress transmission of vibration from the engine due to the movement of the brush cutter during operation.

  According to the invention of claim 3, since the plurality of vibration isolators are arranged in parallel with a certain distance from each other, it is possible to effectively control the torsional vibration due to the torque fluctuation of the engine. .

  According to the invention of claim 4, since the vibration isolator is constituted by a spring, it is possible to realize a compact vibration isolating structure having a high vibration isolating effect while using inexpensive parts.

  According to the invention of claim 5, four winding springs are used as springs, two springs are horizontally disposed on one end side of the engine, and two springs are horizontally disposed on the other end side of the engine. Since the engine can be held in a floating state with respect to the cover, it is possible to greatly reduce transmission of vibration from the engine to the operator.

  According to the invention of claim 6, one end of the spring is attached to the cover via the spring holder, and the other end is fixed to the hole formed in the cylinder of the engine using a screw or a bolt. Two functions of holding the spring and fixing to the cover can be realized at the same time.

  According to the seventh aspect of the present invention, since the internal space on the cylinder rear side in the cover is divided into the suction space and the discharge space by the partition plate, the flow of the wind inside the cover can be rectified in a certain direction. An efficient cooling effect can be obtained.

  According to the eighth aspect of the present invention, since the cover is formed with a flat surface portion that serves as a mounting surface on the lower side, the cover can be stably held when it is directly grounded to the ground or the like. In addition, since the upper end is formed into an acute angle, the upper and lower positions are inevitably determined when the engine is stopped and placed on the ground, so that the muffler side is always at the top, and a good heat dissipation effect Can be achieved.

  According to the ninth aspect of the present invention, since the engine muffler is disposed in the exhaust space, the discharge direction of the engine cooling air and the exhaust direction from the muffler can be set to be the same, and the exhaust and exhaust effects are improved. Can do.

  According to the invention of claim 10, the engine is an upright engine in which the cylinder is arranged in the vertical direction, the partition plate is provided in the horizontal direction so as to extend to the vicinity of the joint portion between the cylinder and the crankcase, and the suction space is on the lower side. In addition, since the discharge space is arranged on the upper side, an efficient cooling air path that sucks in cool air from the lower side and discharges heated air from the upper side can be realized.

  The above and other objects and novel features of the present invention will become apparent from the following description and drawings.

It is a perspective view which shows the external appearance of the brush cutter 1 which concerns on the Example of this invention. It is a longitudinal cross-sectional view which shows the internal structure of the brush cutter 1 which concerns on the Example of this invention. It is a rear view of the brush cutter 1 which concerns on the Example of this invention. It is a top view of the brush cutter 1 which concerns on the Example of this invention, Comprising: The state which removed the upper cover 7 is shown. It is sectional drawing which shows the detailed structure of the vibration isolator 30 of FIG. It is a longitudinal cross-sectional view which shows the internal structure of the brush cutter 101 which concerns on the 2nd Example of this invention. It is a rear view of the brush cutter 101 which concerns on the 2nd Example of this invention. It is a figure for demonstrating the mounting state to the floor of the brush cutter 101 which concerns on 2nd Example of this invention. It is a longitudinal cross-sectional view which shows the internal structure of the brush cutter 201 which concerns on the 3rd Example of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. In this specification, description will be made assuming that the front, rear, left, right, and up and down directions are directions shown in the drawing.

  FIG. 1 is a perspective view showing an appearance of a brush cutter 1 according to the present invention. In FIG. 1, a drive shaft, which will be described later, is passed through a pipe-shaped main pipe 4 (transmission shaft), and the drive shaft is rotated by an engine provided on one end side of the main pipe 4 to be provided at the other end of the main pipe 4. A tip tool such as the cutting blade 2 is rotated. In the vicinity of the cutting blade 2, a scattering protection cover 9 for preventing scattering of the grass that has been cut off is provided. The brush cutter 1 is carried by a shoulder belt (not shown) or the like, and a handle 3 having a substantially U-shape in front view for operation by an operator is attached to the vicinity of the central portion of the main pipe 4. The rotation speed of the brush cutter 1 is controlled by an operator by a throttle lever (not shown) attached to the handle 3. The operation of the throttle lever is transmitted to an engine carburetor (described later) via a wire (not shown).

  The brush cutter 1 includes, for example, a two-cycle small engine (described later), and is covered with a cover 5 provided to cover the entire engine. The cover 5 has a cylindrical shape, and has a shape such that the diameter increases from the small diameter portion on the front side through which the main pipe 4 passes to the vicinity of the center, and is slightly narrowed from the vicinity of the center to the vicinity of the rear end. The cover 5 is provided with an opening only at the rear end, and has a cylindrical axis in the front-rear direction. The engine is held in a state of floating inside the cover 5, and here is held by two left and right vibration isolation devices (described later) fixed to the cover 5 by nuts 34. A fuel tank 27 made of polymer resin such as plastic or metal is attached to the lower side of the cover 5.

  FIG. 2 is a longitudinal sectional view showing the internal structure of the brush cutter 1 according to this embodiment. The engine 10 is a two-cycle small engine, in which the crankshaft 13 is disposed coaxially with the main pipe 4, the cylinder 11 is disposed so as to extend in a substantially vertical direction from the crankcase 14, and the piston 12 is disposed in the vertical direction. Move back and forth. A muffler 16 is attached to the rear side of the cylinder 11, and a carburetor (described later in FIG. 3) is provided on the right side of the cylinder 11. A cooling fan 17 is disposed on the front side of the crankshaft 13, a centrifugal clutch 18 is disposed on the front side of the cooling fan 17, and a drum 19 to which the output of the centrifugal clutch 18 is transmitted. The drum 19 is an output part of the engine 10. The drum 19 is connected to a joint 21 rotatably fixed by a bearing 22, and is connected to a transmission shaft 35 via a flexible shaft 20 on the front side of the joint 21. The flexible shaft 20 has a certain degree of flexibility.

  An ignition coil 23 for supplying a high-voltage current to the spark plug 25 is provided above the cooling fan. The high voltage current generated by the ignition coil 23 is transmitted to the spark plug 25 via the ignition cord 24. In this embodiment, the components provided in the front portion of the engine 10, that is, the cooling fan 17, the centrifugal clutch 18, the drum 19, the joint 21, the bearing 22, the ignition coil 23, and the ignition cord 24 are covered by the casing 8. The casing 8 serves as a housing that forms an air passage for effectively flowing the cooling air generated by the cooling fan 17 to the cylinder 11 and serves as a housing for holding the joint 21. It is attached to cover. The casing 8 is desirably configured to be lightweight with a minimum necessary thickness, and is fixed to the crankcase 14 and the cylinder 11 of the engine 10 with screws or the like.

  A starter 26 is provided on the rear side of the engine 10 and coaxially with the crankshaft 13. The starter 26 connects the reel around which the traction string is wound to the crankshaft 13 of the engine via a clutch, and starts the engine by pulling the traction string. In the present embodiment, the entire starter 26 is accommodated inside the cover 5, and the rear end portion of the starter 26 is located on the front side of the opening surface 43.

  A muffler 16 is provided on the rear side of the cylinder 11 of the engine 10. The muffler 16 reduces exhaust noise when the combustion gas discharged from the cylinder 11 is discharged to the outside, and is made of metal and formed in a box shape. Although not shown in FIG. 2, a plurality of expansion chambers may be provided inside the muffler 16, or a catalyst device may be provided for purifying exhaust gas. In the present embodiment, the entire muffler 16 is accommodated in the cover 5, and the rear end portion of the muffler 16 is located on the front side of the opening surface 43.

  The cover 5 is provided so as to accommodate the entire assembly of the casing 8 and the engine 10, and is formed, for example, in two parts by integral molding of synthetic resin such as plastic. The cover 5 is configured such that it can be divided in the vertical direction from the dividing surface by the lower cover 6 and the upper cover 7. The upper cover 7 is configured in such a shape that the engine 10 can be maintained when it is removed from the lower cover 6, and the lower cover 6 and the upper cover 7 are fixed by fastening members (described later) such as screws or bolts, for example. .

  A fuel tank 27 is fixed to the lower side of the cover 5 by bolts 39. The fuel tank 27 contains a mixed oil of gasoline and oil for two cycles, and the mixed oil is sucked by a hose 28 extending from the carburetor of the engine 10. A filter 29 is provided at the tip of the hose 28 to prevent suction of dust. A cylindrical portion is formed at the tip of the cover 5, and the main pipe 4 is inserted inside the cylindrical portion. At that time, the main pipe 4 and the cover 5 are fixed by the bolt 38 penetrating through a hole formed in the main pipe 4.

  As described above, the entire engine 10 is covered with the cover 5 and the engine components are arranged as described above, so that when the engine 10 is operated, an arrow is placed on the lower half of the opening surface 43 of the cover 5. A flow of intake air as indicated by 46 is generated. Most of the intake air flows as indicated by an arrow 47 and is sucked by the cooling fan 17, and the rest flows into a vaporizer (not shown). The air discharged from the cooling fan 17 flows around a number of heat dissipating fins provided in the cylinder 11 to cool the cylinder 11, for example, flows in the direction of the arrow 48, and finally is discharged in the direction of the arrow 50. Is done.

  The exhaust gas discharged from the muffler 16 and flowing as shown by the arrow 49 joins the air flowing in the direction of the arrow 50. In the present embodiment, the opening surface 43 of the cover 5 is positioned behind the muffler 16 and the starter 26 located at the rear end of the engine 10. As a result, between the vicinity of the rear end portion of the engine 10 and the opening surface 43, a first chamber 41 for the intake air to flow is defined in the lower part, and a second chamber 42 for the exhaust air to flow is formed in the upper part. The Furthermore, a partition plate 40 is provided between the first chamber 41 and the second chamber 42. The partition plate 40 is for completely separating the intake air sent into the engine 10 from the negative pressure generated by the rotation of the cooling fan 17 and the exhaust air discharged from the engine. Thereby, the partition plate 40 is a plate made of synthetic resin such as plastic, and is perpendicular to the moving direction (vertical direction) of the piston 12 and from the opening surface 43 of the cover 5 to the vicinity of the joint portion between the cylinder 11 and the crankcase 14. Arranged to stretch. By providing the partition plate 40 in this manner, the engine 10 can be efficiently cooled, the crankcase 14 can be effectively cooled, and the charging efficiency can be improved.

  FIG. 3 is a rear view of the brush cutter 1 according to the embodiment of the present invention. As can be understood from the rear view, the cover 5 formed in two parts by the upper cover 7 and the lower cover 6 is formed in a cylindrical shape so as to completely cover the whole of the engine 10 and is opened to the rear side. A surface is formed. The upper cover 7 and the lower cover 6 are configured so as to be split vertically on the split surface, and are fixed by a plurality of bolts 37.

  The lower cover and the engine 10 are fixed via a plurality of vibration isolation devices 30 arranged in the horizontal direction. The vibration isolator 30 is preferably arranged so as to be perpendicular to the piston movement direction (vertical direction), one end of which is fixed to the lower cover 6 and the other end is the cylinder 11 of the engine 10 which is a vibration source. Fixed to. The cylinder 11 is arranged upright in the vertical direction, and a spark plug 25 is provided near the top. An exhaust port (not shown) is provided on the rear side of the cylinder 11, and a box-like muffler 16 is directly attached to the exhaust port. An exhaust port 16 a is formed in a part of the muffler 16. A starter 26 is provided on the rear side of the crankcase 14 and coaxially with the crankshaft 13. A puller string 26 a is wound around the starter 26, and the index string 26 a extends through the hole formed in the lower cover 6 to the outside of the lower cover 6. A knob 26b is attached to the tip of the index cord 26a. Thus, since the vibration isolator 30 is arranged in a direction perpendicular to the axis of the transmission shaft 35, the space on the side of the cylinder 11 can be used effectively, and the main body can be configured compactly. Further, by being directly fixed to the cylinder 11 as a vibration source, transmission of vibration from the engine can be effectively suppressed.

  A fuel tank 27 is fixed to the lower side of the lower cover 6 by bolts 39. On the right side of the fuel tank 27, an opening for filling gasoline and oil is provided, and the opening is closed by a cap 27a. The fuel tank 27 is preferably configured to be translucent so that the remaining amount can be easily seen from the outside. Thus, the fuel tank 27 is separated from the engine 10 as the vibration source and disposed on the cover 5 side, so that the weight on the cover 5 side (that is, the handle 3 side) increases, and vibration transmitted to the operator is generated. It becomes possible to reduce.

  A partition plate 40 is disposed between a space (first chamber: suction space) in which the starter 26 is accommodated and a space (second chamber: discharge space) in which the muffler 16 is accommodated. The partition plate 40 is a rectangular flat plate and is held so as to be sandwiched between ribs 6a formed on the inner wall of the lower cover. Since the heat generating part of the engine 10 is usually the cylinder 11 and the muffler 16, it can be understood that the heat generating part is arranged so as to be concentrated on the upper side of the partition plate 40. By arranging in this way, it is possible to effectively exhaust the heat of the heat-generating portion that has become high temperature to the outside of the cover 5 not only during operation of the engine but also when the engine 10 is stopped. At this time, since air is discharged from above the cover 5, air flows into the lower part of the cover 5 by natural convection, so that the engine 10 can be effectively cooled. In this embodiment, the first chamber and the second chamber are arranged in the vertical direction, but the arrangement is not necessarily limited to this. For example, the cylinder 11 of the engine 10 may be arranged horizontally in the left-right direction, and the first chamber and the second chamber may be arranged in the left-right direction. Even in such a case, the intake air and the exhaust air are separated. Can do. In that case, the cross-sectional shape of the cover 5 viewed from the position of FIG. 3 may be an elliptical shape extending in the horizontal direction instead of an elliptical shape extending in the vertical direction.

  FIG. 4 is a top view of the brush cutter 1 according to the embodiment of the present invention, and shows a state where the upper cover 7 is removed. The lower cover 6 is formed with four screw holes 6b for fixing the upper cover 7, and the vicinity of the screw holes 6b protrudes in the left-right direction. Further, as can be understood from the drawing, the engine 10 is fixed to the lower cover 6 by four vibration isolator 30. Two anti-vibration devices 30 are provided on the left and right sides, and one on the left or right side is disposed in front of the center of the cylinder 11 (position of the ignition plug 25) in the front-rear direction, and the remaining one on the left or right side. Is arranged behind the center of the cylinder 11. The two left or right vibration isolator 30 are both arranged in parallel. The vibration isolator 30 is fixed to the lower cover 6 by a nut 34.

  When the engine 10 is started, the piston 12 reciprocates to generate vertical vibrations. The vertical vibration is transmitted to the cover 5 via the vibration isolator 30 fixed to the crankcase 14 and is transmitted to the handle 3 via the main pipe 4 attached to the cover 5. At this time, the vibration isolator 30 can be largely bent up and down to absorb the vertical vibration and reduce the vibration of the handle 3. Furthermore, since the engine 10 is covered by the cover 5, it is possible to block noise from the engine, and noise transmitted to the operator's ear can be reduced. The transmission shaft 35 connected to the engine 10 is partially a flexible shaft, and is deformed following the vertical vibration of the engine 10 so as to cut off the transmission of vibration to the tip side. 4, the transmission shaft 35 can be held at the center.

  FIG. 5 is a cross-sectional view of the vibration isolator 30 of the brush cutter 1. The vibration isolator 30 is mainly composed of a spring 31 and is fixed by a spring holder 32 and a bolt 35. The spring holder 32 is manufactured by integral molding of synthetic resin such as plastic, and an insert bolt 33 is cast therein in advance. The spring holder 32 functions as a fastening tool (insert bolt 33) corresponding to the nut 34 on the one hand, and functions as a fixing means for fixing the spring 31 on the other hand.

  One end of the spring 31 is fixed to the mounting hole 11a of the cylinder 11 (engine side assembly) with a bolt 36. As the bolt 36, for example, a hexagon socket head cap screw with a washer is used, but it may be fixed to the gear case with a screw or other fixing member. It should be noted that an end portion 31 a wound so that the inner diameter of the winding is smaller than the diameter of the head of the bolt 36 is formed at one end of the spring 31 so that the spring 31 can be directly fixed by the bolt 36.

  The other end of the spring 31 is fixed to the lower cover 6 via a spring holder 32. A spiral groove for holding the spring 31 is formed on the outer periphery of the spring holder 32, and the spring holder 32 is arranged so that the winding of the spring 31 reaches the end of the groove of the spring holder 32 on the frame side. Screwed inside. The spring 31 is made of a spring material manufactured in a spiral shape, and is preferably a compression spring. As the material of the spring 31, known spring steel can be used.

  A female screw is formed in the mounting hole 11a and is screwed into a hexagon socket head bolt 36 in which a washer is incorporated. About half of the head (not shown) and the main shaft of the insert bolt 33 is cast into the spring holder 32, and the other half of the main shaft projects outside through the mounting hole 6c formed on the lower cover 6 side. The spring holder 32 is fixed to the spring 31 by tightening the nut 34 from the outside. When tightening the nut 34, it is necessary to tighten the nut 34 while fixing the minus screw groove 33a at the tip of the insert bolt 33 with a tool such as a minus screwdriver so that the spring holder 32 does not rotate together with the nut 34. is there.

  As described above, according to the present embodiment, the engine 10 is held in a floating state by the vibration isolator 30 inside the cover 5, so that the vertical vibration generated in the handle portion can be reduced and noise transmitted to the operator can be removed. It becomes possible. Furthermore, since the engine 10 is completely covered by the cover 5, the cooling efficiency of the engine 10 can be improved.

  Next, a brush cutter 101 according to a second embodiment of the present invention will be described with reference to FIGS. In the following drawings, the same portions as those in the first embodiment are denoted by the same reference numerals, and the repeated description is omitted. FIG. 6 is a longitudinal sectional view showing the internal structure of the brush cutter 101 according to the second embodiment of the present invention. In FIG. 6, the shape of the cover 105 and the shape of the fuel tank 127 are different from those of the first embodiment. The engine 10 has the same configuration as that of the first embodiment. The cover 105 is configured in a cylindrical shape so as to completely surround the entire engine 10, and is arranged so that its axis is in the front-rear direction (the same direction as the main pipe 4). 4 is connected. The rear side of the cover 105 is an opening surface 143. In the first embodiment, the fuel tank 27 (see FIG. 2) is arranged outside the cover 5, but in the second embodiment, the fuel tank 127 is arranged inside the lower cover. The hose 28 extends inside the fuel tank 127 and the filter 29 is provided at the tip of the hose 28 as in the first embodiment.

  FIG. 7 is a rear view of the brush cutter 101 according to the second embodiment of the present invention. Here, it will be noted that the shape of the cover 105 constituted by the lower cover 106 and the upper cover 107 is significantly different from that of the first embodiment. The lower cover 106 is formed to have a horizontal surface 106b on the lower side in order to accommodate the flat fuel tank 127 therein. The horizontal surface 106b is configured to have a predetermined area of a substantially square shape as can be seen in conjunction with FIG. The fuel tank 127 is fixed to the inner wall side of the horizontal surface 106b with screws or the like (not shown).

  The shape of the lower cover 106 viewed from the rear is configured such that the width increases from the partition plate 40 toward the lower portion, and the width d1 in the vicinity of the partition plate 40 is the gold width d2 where the fuel tank 127 is located. Compared to the above, it is configured to satisfy the relationship of d1 <d2. With this configuration, it is possible to ensure a large capacity of the fuel tank 127 while disposing the fuel tank 27 inside the cover 105. Further, the shape of the lower cover 106 is such that the fuel tank 27 can be protected by the cover 105 when the brush cutter 101 is directly grounded to the ground or the like, so that the cover 105 also serves as a tank guard. Furthermore, since there are only other bolts etc. on the outside of the cover 105, and there are no other attachments, not only the appearance is clean, but there are almost no projections that hit the body during work, so an easy-to-use brush cutter realizable.

  The cover 105 is formed so as to be split vertically on the split surface, and the upper cover 107 is configured as a separate part from the lower cover 106. The upper cover 107 is fixed to the lower cover 106 with bolts 139. Also in the second embodiment, the engine 10 is held by the four vibration isolation devices 30. The position where the vibration isolator 30 is provided (between the cylinder 11 and the lower cover 106) is the same as in the first embodiment. In addition, the uppermost part 107a of the upper cover 107 is formed in a sharp pointed shape. By making the uppermost portion 107a of the upper cover 107 have an acute angle, the vertical position is inevitably determined when the engine 10 is stopped and placed on the ground, and the operator places the brush cutter 101 upside down on the ground or the like. It can be prevented, and it can be induced that the muffler 16 side is always located at the upper part, so that heat radiation by natural convection can be surely performed.

  FIG. 8 illustrates this state. FIG. 8A is a diagram illustrating a state in which the brush cutter 101 is established on a placement surface such as the ground, and FIG. 8B is a diagram illustrating a state in which the brush cutter 101 is to be inverted. As can be understood from FIG. 8A, the lower cover 106 is formed with a flat horizontal surface 106b in contact with the placement surface, and the brush cutter 101 can be placed stably. . However, the uppermost portion 107a of the upper cover 107 is formed in an acute angle shape so that the operator cannot place the brush cutter 101 upside down. For this reason, when the brush cutter 101 is placed upside down, it cannot be placed because it is not stable as shown in FIG. As described above, in the second embodiment, the shapes of the lower cover 106 and the upper cover 107 are devised so that the lower cover 106 and the upper cover 107 can be easily placed in the upright state and cannot be placed in the inverted state. As a result, troubles such as difficulty in restartability due to the operator placing the brush cutter 101 in an inverted state can be avoided.

  The upper cover 107 is configured to have a substantially triangular shape when viewed from the back as shown in FIG. 7 so that the upper end has an acute angle. It becomes difficult to accommodate. Therefore, the upper cover 107 is formed with a protruding portion 107b that protrudes in a hemispherical shape on the right side.

  Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 9 is a longitudinal sectional view showing the internal structure of the brush cutter 201 according to the third embodiment. In the brush cutters 1 and 101 of the embodiments described in the first and second embodiments, since the entire engine 10 is covered with the covers 5 and 106, a brush cutter with a clean appearance can be realized. However, if the engine 10 is covered, the heat dissipation when the engine 10 is stopped after work may be adversely affected. Therefore, in the third embodiment, the shape near the upper rear end 207c of the upper cover 207 is bent upward so that heat from the engine 10 and the muffler 16 can be easily dissipated. By adopting such a shape, a chimney effect can be expected, and the flow of the exhaust gas is made as indicated by an arrow 250, and heat due to natural heat radiation from the muffler 16 can be effectively dissipated as indicated by arrows 250a to 250d. it can.

  As described above, in the third embodiment, by changing the shape near the upper end of the opening surface 243 of the cylindrical cover 205, the opening area on the outlet side of the cover 205 can be increased. And a muffler 16 that can easily dissipate heat naturally.

  While the present invention has been described based on a plurality of embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Brush cutter 2 Cutting blade 3 Handle 4 Main pipe 5 Cover 6 Lower cover 6a Rib 6b Screw hole 6c Mounting hole 7 Upper cover 8 Casing 9 Scatter protection cover 10 Engine 11 Cylinder 11a Mounting hole 12 Piston 13 Crankshaft 14 Crankcase 14a Mounting hole 15 Vaporizer 16 Muffler 16a Exhaust port 17 Cooling fan 18 Centrifugal clutch 19 Drum 20 Flexible shaft 21 Joint 22 Bearing 23 Ignition coil 24 Ignition cord 25 Spark plug 26 Starter 26a Index string 26b Knob 27 Fuel tank 27a Cap 28 Hose 29 Filter 30 Anti-vibration device 31 Spring 31a End 32 Spring holder 33 Insert bolt 33a Minus thread groove 34 Nut 35 Transmission shaft 36, 7, 38, 39 Bolt 40 Partition plate 41 First chamber 42 Second chamber 43 Opening surface 101 Brush cutter 105 Cover 106 Lower cover 106b Horizontal surface 107 Upper cover 107a Uppermost portion 107b Protruding portion 127 Fuel tank 139 Bolt 143 Opening surface 201 Cutting Dispenser 205 Cover 206 Lower cover 207 Upper cover 207c Upper rear end vicinity 243 Opening surface

Claims (10)

Engine,
An output transmission shaft that transmits the output of the engine and a tool is attached to the tip;
A main pipe through which the output transmission shaft is inserted;
A brush cutter having a hand-held handle provided at an intermediate position of the main pipe,
Provide a cylindrical cover having an axis in the front-rear direction so as to surround the entire engine,
The brush cutter is characterized in that the engine is held by a plurality of vibration isolation devices inside the cover. The front side of the cover is squeezed and connected to the main pipe, the rear side of the cover is opened,
The brush cutter according to claim 1, wherein the vibration isolator is disposed in a direction perpendicular to an axis of the output transmission shaft.   The brush cutter according to claim 2, wherein the plurality of vibration isolators are arranged in parallel at a predetermined interval.   The brush cutter according to claim 2 or 3, wherein the vibration isolator is a spring. One end of the spring is fixed near the joint of the cylinder and crankcase of the engine, and the other end is fixed to the cover,
4. Four winding springs are used as the springs, two springs are horizontally disposed on one end side of the engine, and two springs are horizontally disposed on the other end side of the engine. Item 5. A brush cutter according to Item 4. One end of the spring is attached to the cover via a spring holder,
The brush cutter according to claim 5, wherein the other end of the spring is fixed to a hole formed in a cylinder of the engine using a screw or a bolt. The inner space on the cylinder rear side in the cover is partitioned by a partition plate,
The brush cutter according to any one of claims 1 to 6, wherein one of the compartments is used as a space for sucking air and the other is used as a space for discharging air and exhaust gas.   8. The brush cutter according to claim 7, wherein the cover has a flat portion formed on the lower side as a mounting surface, and an upper end portion formed in an acute angle shape.   The brush cutter according to claim 8, wherein a muffler of the engine is disposed in the discharge space. The engine is an upright engine in which the cylinder is arranged in a vertical direction, and the partition plate is provided in a horizontal direction so as to extend to the vicinity of the cylinder and the crankcase joint,
The brush cutter according to claim 9, wherein the suction space is disposed on the lower side and the discharge space is disposed on the upper side.

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